This project focuses on gender differences in vocal communication in adulthood and during development, on the role of individual experience in the acquisition of adult vocal skills, and on the development of computer-based algorithms for acoustic parameter extraction and analysis. Major findings this year were: A computer program developed for automatic extraction of acoustic parameters and refined in this laboratory for the vocalizations of infant rhesus macaques was used to analyze the development of the most prominent infant call given during periods of social separation. These analyses revealed that a large number of acoustic parameters change with development. Some parameters follow a regular trajectory toward adult values, while others change rather abruptly to more adult-like values. Identification of individual infants on the basis of differences in the structure of their calls can be accomplished even during the neonatal period. The 'attribute hypothesis' (Newman and Goedeking, 1992) was supported by a study of marmoset vocal behavior, wherein separate acoustic parameters encoded context and gender.